Patent GB-259650-A (GB)
Title: Improvements in or relating to electric selective systems applicable to type printing telegraphs and other purposes
IPC: H04L17/30
Filed: 1925-07-06
Abstract: 259,650. Semat, L. July 6, 1925. Type-printing telegraphs.-An electric selector for selecting one of a number of circuits, such as the circuits of electromagnets for operating the striking hammers of a type-writer, comprises a number of groups of relay units, arranged successively, the number of units in successive groups increasing in accordance with the progression 1, 2, 4, 8 &c. Selection is determined by a constant number of impulses which are transmitted in varying polarity combinations over a single line. The first unit selects one or other unit in the second group according to the polarity of the first impulse and this unit extends in like manner the impulsing circuit to one of the relays of the third group upon receipt of the second impulse and so on. Each relay unit comprises impulse magnets 1. 1<1>, Fig. 3, which control an armature 5 pivoted between the arms 6. 7 of the pivoted U-shaped armature 8 of an electromagnet 2. The position of a two-way switch 21, which extends the impulsing circuit to the subsequent relay group, is determined by an electromagnet 15 or a permanent magnet mounted on the switch 21 and attracted or repelled by the magnet 1<1> according to the polarity of the signal impulse. The switch 21 also controls the circuit of an electromagnet 3 which operates a switch 13<1> included in the circuit to be selected. Instead of the magnet 3, a mechanical connection may be provided between the switches 21, 13<1>. Selection. Assuming it is desired to select the electromagnet 35 shown in thick lines, two impulses of polarity +, -, are transmitted over the line 4. Normally the arm 6 of the armature 8 is in contact with the armature 5. The first impulse energizes the electromagnets 1, 1<1> of the unit A and causes the attraction of the armature 5 and, in consequence, the movement of the armature 8 to establish at the contact 12 12<1>, a circuit for a locking magnet 2. The armature 5 also closes, at the contact 5<1>, the circuit of the electromagnet 15 on the switch 21. The polarity of the magnet 15 is such that the magnet is repelled by the magnet 1<1> upon the receipt of the first impulse and the switch 21 is moved into contact with the contact 7<11>. When the switch 21 is operated a circuit for the electromagnet 3 is completed at the contacts 25, 26 and the switch 13<1> is moved into engagement with the contact 14<11> to extend the operating circuit to the switch 13<1> of the unit C. Upon the cessation of the first impulse, the armature 5 is moved by a spring 9 into contact with the arm 7 of the armature 8 and the impulsing circuit is extended to the unit C. The switch 21 is held in its set position by the magnet 3. The next impulse being of negative polarity tends to attract the electromagnet 15 in the unit C and the switches 21, 13<1> are left in their normal positions. The actuating circuit of the magnet 35 is thus prepared and the impulsing circuit is extended to electromagnet 42, 42<1>. Closing the selected circuit. A supplementary positive impulse is transmitted at the end of the signal to energize the magnets 42, 42<1> which actuate the armature 5 to close the circuit of an electromagnet 15 on a pivoted switch lever 38. The electromagnet 42<1> repels the magnet 15 and operates the switch 38 to close the actuating circuit of the selected magnet 35 at the contacts 39. Releasing the equipment. The switch 38 also closes contacts 43, 44 in the circuit of an electromagnet 45. The magnet 45 attracts its armature 46 and thereby engages a pivoted catch 48 with a projection 49 on a switch 34 which is connected in the circuit of the locking magnets 2, 3. When the supplementary impulse ceases the armature 46 is released and the catch 48 opens the switch 34 to restore the apparatus to normal. During its movement the catch 48 escapes the projection 49 and the switch is again closed ready for the next selective operation. Modified systems, Figs. 5 and 6. In a modification two series D, E of relay groups may be employed, the relays being arranged in 2n accordance with the progressions 1, 2, 4 - - - 2 2p and 1, 2, 4 - - - in order to control 2n x 2P 2 circuits. The contacts 7, 7<1> of the final group of relays of the series D are connected by a common lead 52 to the switch 21 of the first relay unit of the series E so that the signal impulses are led to the second series after passing through the first series. As shown in Fig. 5, the contacts of the switches 13<1> in the series D are connected to electromagnets 35 which operate rods 53 carrying switches 54. The switches 54 co-operate with contacts which are connected through the units to be selected to wires 55 leading to the switches 13<1> of the series E. Fig. 6 shows a similar arrangement of relays connected to a rotary distributor. The series D of relays select a particular group of contacts 61 on the distributor and the series E picks out a particular contact 59, associated with the selected group 61. The rotary switch arm 63 bridges the contacts 59, 60 and completes the circuit of the selected magnet 35. Transmitting apparatus, Fig. 7. In the form shown the transmitter comprises a plurality of keys 64 having insulated and conductive portions arranged in a manner characteristic of the key. The keys co-operate with wires 77, 78 &c. connected to corresponding relays 70. Each relay has an armature 69 adapted to engage one or other of two contacts 73, 74 which are connected to opposite poles of two batteries 71, 72. The armatures 69 are connected to corresponding contacts 75 of a distributor. When a key, for example the key 64, is operated, a circuit is first completed from the battery 65, wire 66, key 64, wire 77, to the corresponding relay 70 which atracts its armature and marks the corresponding contact on the distributor with positive potential from the battery 72. Further depression of the key energizes the fourth magnet 70 to mark the fourth contact on the distributor with positive potential, the other contacts being at negative potential by reason of the engagement of the unattracted armatures 69 with the contacts 73. When the key is fully depressed a circuit is completed from the battery 65, wire 66, key 64, wire 67, to the electromagnet 68 which withdraws a catch from the distributor arm 76. During rotation the arm 76 co-operates with the contacts to transmit over the line 4 a signal code which is characteristic of the depressed key. Specification 205,048 is referred to.